'Black Box' Drug Warning Labels Applied Inconsistently: Study

FRIDAY Feb. 4, 2011 -- Safety labels that outline concerns about medications, known as "black box warnings," are not always consistent within drug categories, a new study suggests.

These warnings should be rendered uniform for all medications within a single class of drugs, according to a team of researchers from Greece and the United States. The team also advised that supplemental warnings (for example, following a drug withdrawal) should be added in a reasonable timeframe.

The research team published their report Feb. 2 in the Journal of General Internal Medicine.

"Our findings imply that the process of black box warning acquisition requires transparent and systematic rules, as well as clear justification for the presence of, or lack of evidence for, specific major risks for individual drugs," the research team led by Orestis Panagiotou from the University of Ioannina's School of Medicine in Greece, said in a journal news release.

The authors pointed out that black box warnings are the strongest tool the U.S Food and Drug Administration has to issue consumer safety warnings and outline drug risks. Most warnings are issued per class of drugs, rather than for an individual drug, because concerning side effects usually apply broadly to a type of drug rather than to a single medication.

Therefore, the team focused on analyzing black box warning labels placed on drugs that all fell within the same drug class.

The investigators examined 20 different drug classes that in total covered 176 medications, all chosen from data included in the USA's "Top 200 Drugs for 2008 by Sales" report.

Half of the 20 drug classes had at least a single black box warning issued; the other half had no such warnings.

Black box warning inconsistencies were found in nine drug classes, with 15 specific warnings not uniformly evident on the labeling of all drugs that fell within each specific class.

In two-thirds of these (10 of the 15), the information was, in fact, noted on the labels in a different place, as either a simple warning or plain text. The rest did not include the warnings anywhere on the label.

What's more, specific drugs subject to a withdrawal from the market were not typically outfitted with a black box warning prior to a withdrawal, the team found. And drugs similar to the withdrawn medication were frequently not labeled with a relevant black box warning referencing the concerns that led to the withdrawal in question.

A significant time lag in the posting of black box warnings was also commonly observed (ranging from two months to 14 years) for drugs that fell into classes in which similar drugs were subject to the warning.

The authors suggested that if a drug is in the same class as another drug that requires a black box warning, but the warning does not apply to that particular medication, the warning label should specifically explain why this is the case to ease consumer confusion.

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